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Abstract

"Energetic ionic liquids capable of dual-mode chemical monopropellant or bipropellant and electric electrospray rocket propulsion are investigated. Following an extensive literature review, ionic liquids [Bmim][dca], [Bmim][NO₃], and [Emim][EtSO₄] are selected for study since their physical properties align well with the current state-of-the-art in chemical and electrospray propellants. Simulations show that these liquids will not be useful for monopropellant propulsion due to the prediction of solid carbon formation in the exhaust and performance 13-23% below that of hydrazine. Considering these ionic liquids as a fuel component in a binary monopropellant mixture with hydroxyl ammonium nitrate shows 1-4% improved specific impulse over some 'green' monopropellants, while avoiding volatility issues and reducing the number of electrospray emitters by 18-27% and power required by 9-16%, with oxidizing ionic liquid fuels providing the greatest savings.

Mixtures of HAN with ionic liquid fuels [Bmim][NO₃] and [Emim][EtSO₄] are synthesized and tested for catalytic decomposition in a micro-reactor to investigate their potential for use as monopropellants. Two unsupported catalyst materials were tested with the novel propellants: rhenium and iridium. For the [Bmim][NO₃]/HAN propellant, 30 µL droplets on rhenium preheated to 160⁰C yielded a pressure rise rate of 26 mbar/s, compared to 14 mbar/s for iridium and 12 mbar/s for no catalyst. [Emim][EtSO₄]/HAN propellant shows slightly less activity at 160⁰C preheat temperature, yielding a pressure rise rate of 20 mbar/s, 4 mbar/s, and 2.5 mbar/s for injection onto rhenium, iridium, and the thermal plate, respectively"--Abstract, page iv.